Garmin GPS installations woes

[Ken Cross]

I just tried to interface my new Garmin GPSMAP 441S with my almost new Lowrance LVR250 and I'm a little frustrated.

The Lowrance VHF has NEMA out and in (+) and (-) (4 wires)
The Garmin has NEMA Rx/A (+) and NEMA Tx/A(+) and shows a NEMA ground(3 wires)

I tried leaving the (-) connections open and have no interface. I tried grounding them and no interface. Do I need a pair of transformers to go from a balanced signal to the grounded Garmin type? If so any idea what impedance? Where can I get them?

Both units claim to be NEMA 183 compliant.

Also I tried to mount the Garmin on my aft cabin bulkhead in the cockpit and the mounting bracket is too short (or the cable strain relief is too long) to accommodate bulkhead mounting. I just can't believe I'm the first to complain about this (the Garmin Tech support guy was of no help whatsoever for either problem. The only conclusion tech support had was to return it to the dealer.

I'd love some helpful suggestions.

 

[twalker H260]

based on my read of your manuals the following are the wires to join. Note the garmin black wire serves as power ground(-) and nmea - for both transmit and receive.
You will also need to set both the radio and garmin to use nmea 0183. Page 29 of radio manual and Pages 51 on in the garmin owners manual.

Lowrance. * * * * * * *Garmin
Nmea out. * * * * * * * Nmea in
+ orange. > * * +brown
-black. * * * * * *> * * *-Black (ground)

Nmea in. * * * * * * * * * Nmea out
+yellow. * * * * >* * * * +Blue
- green. * * * * >. * * *-Black (ground)

Can't help you with the bracket/strain relief.

 

[Ken Cross]

Thanks Twalker, I'll go back to the boat and see if that's how I connected it. I did put a meter on the wiring and I do see activity on the output from the Garmin. I haven't put a scope on it however. That indicates the radio may not be set up right or the plotter output contains the wrong data.
Ken

As for the bracket I may just fabricate a new one. I like the unit, I'm just amazed they would not allow for a bulkhead mount. They don't even sell options for it.

 

[CarlN]

I'm imagine you've already looked, but I would double check the NMEA 0183 settings on the Garmin under Configure->Communications->Serial Port.

I had the dickens of a time with a Garmin not transmitting to a VHF until I tried changing the speed from "High Speed" to "Standard".

I would also turn off any output sentences you don't need in case it's confusing the Lowrance.

Carl

 

[FourPoints]

As for the bracket I may just fabricate a new one. I like the unit, I'm just amazed they would not allow for a bulkhead mount. They don't even sell options for it.

Look at the flush mount kit, that is what I am using & love it. Much cleaner than a surface mount, and very secure as you cannot remove the unit unless you have access to the back of it.